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July 13, 2017

Delaware-sized iceberg breaks free from Antarctic ice shelf

by Chuck Bednar

One of the largest icebergs ever recorded – a massive chunk of frozen water that is roughly the same size as the state of Delaware and which weighs more than a trillion tons – has broken away from the Larsen C Ice Shelf in Antarctica, experts have confirmed using NASA satellites.

According to BBC News and the Los Angeles Times, the 1.12 trillion ton iceberg (which is large enough to completely fill Lake Erie twice) was confirmed to have broken away from the ice shelf on Wednesday and is now floating freely in the Weddell Sea, north of West Antarctica.

The calving event took place sometime between Monday, July 10 and Wednesday, July 12, and was confirmed Project Midas, a group of scientists from Swansea and Aberystwyth Universities in the UK, using the NASA/NOAA Suomi National Polar-orbiting Partnership satellite’s Visible Infrared Imaging Radiometer Suite instrument, the US space agency said in a statement.

Scientists had been monitoring the condition of the Larsen C ice shelf for years, and particularly since January. That’s when a rift in the glacier grew by approximately 120 miles, which left the iceberg attached to the larger ice shelf by a less than three-mile-wide string of frozen water.

“We have been anticipating this event for months, and have been surprised how long it took for the rift to break through the final few kilometers of ice,” Project Midas lead investigator Adrian Luckman said in a blog post. “We will continue to monitor both the impact of this calving event on the Larsen C Ice Shelf, and the fate of this huge iceberg.”

Was climate change a factor, and what happens to the region now?

Although the iceberg poses no immediate threat to global sea levels, scientists told the Times that they are concerned that the massive glacier – one of the largest ever recorded – could have a long lasting impact on the continent and may be a harbinger of what’s to come due to climate change.

“When they break up, you just open the flood gates,” Eric Rignot, a glaciologist at the University of California, Irvine and a research scientist at NASA’s Jet Propulsion Laboratory (JPL), told the newspaper. While the Larsen C ice shelf is not in immediate danger, Rignot added, “more bergs will detach; it will become weaker and eventually fall apart in a domino effect.”

According to Luckman, the size of the iceberg makes it “difficult to predict” how it will behave in near future. “It may remain in one piece but is more likely to break into fragments. Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters.” However, as the Times noted, this calving event reduced Larsen C’s size by at least 12% and has caused some concern that the rest of the shelf could ultimately become destabilized.

“In the ensuing months and years, the ice shelf could either gradually regrow, or may suffer further calving events which may eventually lead to collapse – opinions in the scientific community are divided,” Luckman said. “Our models say it will be less stable, but any future collapse remains years or decades away.”

However, one thing that Project Midas glaciologist Martin O’Leary emphasized is that this was a natural event and that he and his colleagues found no link to man-made climate change. Even so the calving event has pushed Larsen C’s extent back further than at any other time in history, and the research team believes that this will give them an opportunity to study how the glacier will be affected by rising air and ocean temperatures.